Intermolecular additions of the O-H bonds of phenols and alcohols and the N-H bonds of sulfonamides and benzamide to olefins catalyzed by 1 mol % of triflic acid and studies to define the relationship between these reactions and those catalyzed by metal triflates are reported. Cyclization of an alcohol containing pendant monosubstituted and trisubstituted olefins catalyzed by either triflic acid or metal triflates form products from addition to the more substituted olefin, and additions of tosylamide catalyzed by triflic acid or metal triflates form indistinguishable ratios of the two N-alkyl sulfonamides.

We report a catalyst for intermolecular hydroamination of vinylarenes that is substantially more active for this process than catalysts published previously. With this more reactive catalyst, we demonstrate that additions of amines to vinylarenes and dienes occur in the presence of potentially reactive functional groups, such as ketones with enolizable hydrogens, free alcohols, free carboxylic acids, free amides, nitriles, and esters. The catalyst for these reactions is generated from [Pd(eta(3)-allyl)Cl](2) (with or without added AgOTf) or [Pd(CH(3)CN)(4)](BF(4))(2) and Xantphos (9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene), which generates complexes with large P-Pd-P bite angles. Studies on the rate of the C-N bond-forming step that occurs by attack of amine on an eta(3)-phenethyl and an eta(3)-allyl complex were conducted to determine the effect of the bite angle on the rate of this nucleophilic attack. Studies on model eta(3)-benzyl complexes containing various bisphosphines showed that the nucleophilic attack was faster for complexes containing larger P-Pd-P bite angles. Studies of substituted unsymmetrical and unsubstituted symmetrical model eta(3)-allyl complexes showed that nucleophilic attack on complexes ligated by Xantphos was faster than on complexes bearing ligands with smaller bite angles and that nucleophilic attack on unsymmetrical allyl complexes with larger bite angle ligands was faster than on unsymmetrical allyl complexes with smaller bite angle ligands. However, monitoring of catalytic reactions of dienes by (31)P NMR spectroscopy showed that the concentration of active catalyst was the major factor that controlled rates for reactions of symmetrical dienes catalyzed by complexes of phosphines with smaller bite angles. The identity of the counterion also affected the rate of attack: reactions of allylpalladium complexes with chloride counterion occurred faster than reactions of allylpalladium complexes with triflate or tetrafluoroborate counterion. As is often observed, the dynamics of the allyl and benzyl complexes also depended on the identity of the counterion.

Detailed studies have been conducted to determine the activity of palladium catalysts for the amination of five-membered heterocyclic halides and to determine the factors that control the scope of this reaction. Palladium-catalyzed aminations of the electron-rich furanyl, thiophenyl, and indolyl halides and of the related 2-halogenated thiazoles, benzimidazole, and benzoxazole have been shown to occur with a subset of amines. Various combinations of palladium precursors and P(t)Bu(3) were tested as catalysts for reaction of 3-bromothiophene with N-methylaniline, and the fastest reactions occurred with the Pd(I) dimer, [PdBr(P(t)Bu(3))](2). The fastest aminations of thiazoles, benzimidazoles, and benzoxazoles occurred with the combination of palladium trifluoroacetate and P(t)Bu(3) as catalyst.

The transition metal-catalyzed anti-Markovnikov hydroamination of unactivated vinylarenes with a rhodium complex of DPEphos is reported. The reaction of electron-neutral or electron-rich vinylarenes with a variety of secondary amines in the presence of catalyst forms the products from anti-Markovnikov hydroamination in high yields. Reactions of morpholine, N-phenylpiperazine, N-Boc-piperazine, piperidine, 2,5-dimethylmorpholine, and perhydroisoquinoline reacted with styrene to form the amine product in 51-71% yield. Reactions of a variety of vinylarenes with morpholine generated amine as the major product. Reactions of morpholine with electron-poor vinylarenes gave lower amine:enamine ratios than reactions of electron-rich vinylarenes at the same concentration of vinylarene, but conditions were developed with lower concentrations of electron-poor vinylarene to maintain formation of the amine as the major product. Reactions of dimethylamine with vinylarenes were fast and formed amine as the major product. Mechanistic studies on the hydroamination process showed that the amine:enamine ratio was lower for reactions conducted with higher concentrations of vinylarene and that one vinylarene influences the selectivity for reaction of another. A mechanism proceeding through a metallacyclic intermediate that opens in the presence of a second vinylarene accounts for these and other mechanistic observations.

Transition metal-catalyzed amination of allylic compounds via a pi-allylmetal intermediate is a powerful and useful method for synthesizing allylamines. Direct catalytic substitution of allylic alcohols, which forms water as the sole coproduct, has recently attracted attention for its environmental and economical advantages. Here, we describe the development of a versatile direct catalytic amination of both aryl- and alkyl-substituted allylic alcohols with various amines using Pt-Xantphos and Pt-DPEphos catalyst systems, which allows for the selective synthesis of various monoallylamines, such as the biologically active compounds Naftifine and Flunarizine, in good to high yield without need for an activator. The choice of the ligand was crucial toward achieving high catalytic activity, and we demonstrated that not only the large bite-angle but also the linker oxygen atom of the Xantphos and DPEphos ligands was highly important. In addition, microwave heating dramatically affected the catalyst activity and considerably decreased the reaction time compared with conventional heating. Furthermore, several mechanistic investigations, including (1)H and (31)P{(1)H} NMR studies; isolation and characterization of several catalytic intermediates, Pt(xantphos)Cl(2), Pt(eta(2)-C(3)H(5)OH)(xantphos), etc; confirmation of the structure of [Pt(eta(3)-allyl)(xantphos)]OTf by X-ray crystallographic analysis; and crossover experiments, suggested that formation of the pi-allylplatinum complex through the elimination of water is an irreversible rate-determining step and that the other processes in the catalytic cycle are reversible, even at room temperature.